Carburetor drain

ABSTRACT

A carburetor includes a carburetor bowl, a fuel supply pipe, a fuel drain pipe, and a valve. The carburetor bowl is configured to store fuel and provide the fuel to an air passage. The fuel supply pipe is connected a fuel tank and the carburetor bowl. The fuel drain pipe is connected to the carburetor bowl and the fuel supply line. The valve for the fuel drain pipe is configured to open and close in response to an orientation of the carburetor.

CROSS REFERENCE TO PRIOR APPLICATIONS

This application is a continuation under 37 C.F.R. § 1.53(b) and 35U.S.C. § 120 of U.S. patent application Ser. No. 16/560,334, which is acontinuation of U.S. patent application Ser. No. 15/923,748 filed Mar.16, 2018 which claims priority benefit of Provisional Application No.62/477,154 filed Mar. 27, 2017 hereby incorporated by reference in theirentirety.

FIELD

This disclosure relates in general to a carburetor or a device thatmixes fuel and air for an internal combustion engine, and morespecifically, to apparatus and techniques for draining a bowl of acarburetor to remove stale fuel from the bowl.

BACKGROUND

A carburetor regulates the speed and volume of air drawn into aninternal combustion engine, which controls the amount of fuel that ismixed with the air and provided to the combustion chamber of theinternal combustion engine. The carburetor may include a bowl thathouses a quantity of fuel at any given time when the engine is runningso that fuel is always available and ready for mixing with the flow ofair.

As a consequence of fuel in the bowl always available for use, some fuelmay remain in the bowl after the engine is no longer running. Fuel thatremains in the bowl for a long period of time may become stale. Longperiods of time may occur during the off-season, for example, when anengine is not used during winter. Several problems may arise with stalefuel. The stale fuel may lose volatility and fail to provide sufficientcombustion for operation of the engine. The stale fuel may at leastpartially evaporate and leave behind sediments or residue that clogcomponents of the carburetor.

The apparatus and techniques described herein prevent or lessen theeffects of stale fuel in the bowl of a carburetor.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments are described herein with reference to thefollowing drawings.

FIG. 1A illustrates a side view of an engine including a carburetor.

FIG. 1B illustrates a top view of the engine of FIG. 1A.

FIG. 2 illustrates the engine mounted on a rotary lawnmower.

FIG. 3A illustrates an example carburetor for a running state.

FIG. 3B illustrates an example valve for the carburetor of FIG. 3A.

FIG. 4A illustrates an example carburetor for a tipped up state.

FIG. 4B illustrates an example valve for the carburetor of FIG. 4A.

FIGS. 5A and 5B illustrate another example carburetor.

FIG. 6 illustrates a cross section of the carburetor in a non-drainingposition.

FIG. 7 illustrates a cross section of the carburetor and tilted enginein a draining position.

FIGS. 8A and 8B illustrate bowl vent locations in the carburetor.

FIG. 9A illustrates a top view of an engine including a recoil pump.

FIG. 9B illustrates a three-dimensional view of the engine including therecoil pump.

FIG. 10 illustrates a blower housing mounted fuel recirculation system.

FIGS. 11A and 11B illustrates three-dimensional views of the blowerhousing mounted fuel recirculation system of FIG. 10.

FIG. 12A illustrates a deactivated position of the recoil pump at theend of the discharge stroke.

FIG. 12B illustrates an activated position of the recoil pump at the endof the section stroke.

FIG. 13A illustrates the operation of the recoil pump in the dischargestroke.

FIG. 13B illustrates the operation of the recoil pump in the suctionstroke.

FIG. 13C illustrates an exploded view of a recoil pump.

FIG. 13D illustrates a top view of the recoil pump of FIG. 13C and theblower housing.

FIGS. 14A and 14B illustrate the fuel recirculation system mounted onthe fuel tank of an engine.

FIGS. 15A and 15B illustrate another embodiment of fuel recirculationsystem.

FIGS. 16A and 16B illustrate a fuel tank mounted pump for the embodimentof FIGS. 15A and 15B.

FIGS. 17A and 17B illustrate detailed views for the fuel tank mountedpump.

FIG. 18 illustrates an example flowchart for operation of an orientationcontrolled carburetor drain.

FIG. 19 illustrates an example flowchart for a recoil actuatedcarburetor drain pump.

FIGS. 20A and 20B illustrate an engine including a recirculation systemusing an enclosed fluid.

FIG. 21 illustrates an example recirculation system using an enclosedfluid in a first state.

FIG. 22 illustrates an example recirculation system using an enclosedfluid in a second state.

DETAILED DESCRIPTION

FIGS. 1A and 1B illustrates an engine 10. The engine 10 includes variouscomponents including a carburetor 11, a fuel tank 15, a recoil starter13, and an air filter compartment 14. Additional, different or fewercomponents may be included.

FIG. 2 illustrates the engine 10 mounted on a rotary lawnmower 19 and across section of the fuel system where the carburetor fuel inlet valveis open to allow fuel to drain from the bowl to the fuel tank. A driveshaft 28 of the engine 10 may be coupled with a blade adapted to rotateunder the force of the engine 10 and cut grass or other vegetation. Therotary lawnmower is in a tipped-up or storage orientation such that thelawnmower 19 is tipped on one end. The tipped-up or storage orientationplaces the wheels 29 of the lawnmower in a vertical orientation (e.g.,front wheels are vertically spaced from the rear wheels) as opposed to ahorizontal orientation (e.g., front wheels are horizontally spaced fromthe rear wheels) when the lawnmower 19 is in operation. In the tipped-upor storage orientation, a support portion 24 (e.g., supporting device)of the lawnmower 19 rests on, or is supported by, floor or ground 22.The support portion 24 may be coupled to or integrated with thehandlebar or handles for pushing the lawnmower 19.

FIG. 3A illustrates an example carburetor 11 including an air passage25, a carburetor bowl 12, a fuel supply line 23, a carburetor drain line21 and a valve 20. The valve 20 is coupled to the carburetor drain line21. Additional, different or fewer components may be included.

The air passage 25 is a pipe that receives a flow of air and mixes fuelfrom a fuel pipe with the air to supply the fuel and air mixture to theengine 10. The air passage 25 may include a narrow portion (e.g., aventuri), which increases the speed of the flow of the air and creates avacuum (e.g., partial vacuum) or pressure that pulls fuel into the flowof air to create the fuel and air mixture. The ratio of air to fuel maybe adjusted by an upstream air flow valve (e.g., choke plate) in the airpassage upstream in the direction of air flow from the fuel pipe. Whenthe upstream air flow valve is more in a closed position, less air flowis present in the air passage 25 and/or relatively more fuel is pulledin by the low pressure, which causes a lower ratio of air to fuel (e.g.,richer fuel and air mixture). When the upstream air flow valve is morein a closed position, less air flow is present in the air passage 25and/or relatively more fuel is pulled in by the low pressure, whichcauses a lower ratio of air to fuel (e.g., richer fuel and air mixture).When the upstream air flow valve is more in an open position, more airflow is present in the air passage 25 and/or relatively less fuel ispulled in by the low pressure, which causes a higher ratio of air tofuel (e.g., leaner fuel and air mixture).

The ratio of air to fuel may be adjusted by a downstream air flow valve(e.g., throttle plate) in the air passage downstream in the direction ofair flow from the fuel pipe. As the downstream air flow valve is more inan open position, more air flows through the air passage 25, picking upmore fuel, and a larger volume of fuel and air mixture is provided tothe engine 10.

The fuel pipe of the carburetor 11 connects the air passage 25 to thecarburetor bowl 12. The carburetor bowl 12 is connected to a fuel supplyline 23 that is connected to and receives a supply of fuel from a fueltank. The carburetor bowl 12 may be a float feed chamber that includes afloat and valve. The float is connected to the valve. The float has adensity less than the fuel. As the fuel level in the carburetor bowl 12sinks, from supply fuel to the fuel pipe and ultimately the engine 10,the float moves and actuates the valve (e.g., open the valve) with thefuel supply line 25. When the valve is actuated, more fuel flows fromthe fuel supply line 25 to the carburetor bowl 12. As the carburetorbowl 12 fills, or is full, the float rises, closes the valve, and thesupply of fuel to the carburetor bowl 12 switches off again.

The carburetor 11 also includes a secondary fuel line (e.g., carburetordrain line 21) and a secondary valve (e.g., valve 20). The carburetordrain line 21 and valve 20 are configured to drain fuel from thecarburetor bowl 12. The carburetor drain line 21 and valve 20 may drainthe carburetor bowl 12 when the engine 10 is not in a running state. Thecarburetor drain line 21 and valve 20 may drain stale fuel ornon-combustible fuel from the carburetor bowl 12. The carburetor drainline 21 and valve 20 may drain the carburetor bowl 12 when the engine 10is in a predetermined orientation. The orientation may be an orientationother than upright. The orientation may be a storage orientation or atipped-up orientation (e.g., for lawnmower 19).

The stale or non-combustible fuel may have a volatility below athreshold value. The volatility of the fuel may be measured in reedvapor pressure or an absolute vapor pressure of a chamber including thefuel that has not be evacuated. The volatility of the fuel may beinversely related to the Reid vapor pressure. The absolute vaporpressure increases due to factors such as time and heat. Starting anengine is more difficult as the absolute vapor pressure increases.

FIG. 3A illustrates an example carburetor in an operating orientation.FIG. 4A illustrates the example carburetor in a tipped-up or storageorientation.

A storage orientation or a tipped-up orientation may occur when anapparatus including the engine 10 is stored in a different orientationthan when in use or in operation with the engine 10 is running. In oneexample, the storage orientation is vertical and the operationorientation is horizontal. In the example of a lawnmower, more than twowheels (e.g., three or four wheels) may rest on the ground in theoperation orientation and two or fewer wheels may rest on the ground inthe storage orientation. The lawnmower may include a third point ofsupport (or more) from an additional stand. The additional stand maymate with the lawnmower and a supporting device integrated with thelawnmower. The additional stand may be rotatable about one or more ofthe wheels. The storage orientation may have a smaller footprint thanthe operation orientation. For example, the space in a horizontal plane(e.g., the plane perpendicular to the direction of gravity) required bythe apparatus in the storage orientation is less than the space in thehorizontal plane required by the apparatus is the operation orientation.Examples other than lawnmower include all terrain vehicles, golf carts,garden equipment or other wheel supported devices with small engines.

FIG. 3B illustrates an example valve 20. The valve 20 may include acheck ball 121, a pocket or passage 123, and a plug 125. The valve 20may be a check valve adapted to permit flow in one direction and not theother direction. For example, the valve may permit flow away from thecarbonator bowl 12 and not toward the carburetor bowl 12. Additional,different, or fewer components may be included, and a variety of checkvalves or other types of valves may be used in place of the valve shownin FIG. 3B.

The valve 20 uses gravity to move the check ball 121 on a sealingsurface or seat 124 from a position to stop flow in one direction as inFIG. 3B, to a position, typically 90 degrees from the stop flowdirection, where gravity causes the check ball to move into a pocket orpassage 123 outside of the main flow passage 126 to allow fluid to flow.A plug 125 has a semi-spherical surface to locate the ball in the flowposition. The plug 125 provides a method to form the sealing seat 124 inthe valve body 20.

In one example alternative to the check valve illustrated in FIG. 3B, aswinging gate type check valves may perform a similar function. Theswinging gate may include a hinge that allows a gate to open and closein the direction of the flow.

The valve 20 may be a gravity controlled check valve (e.g., gravitysensing device) that allows flow in one direction only in a particularorientation with respect to gravity. The valve 20 may operate or beactuated in response to gravity. When the valve 20 (and carburetor 11)is in a first orientation, the valve 20 is in a first state (e.g., openstate), and when the valve 20 (and carburetor 11) is in a secondorientation, the valve 20 is in a second state (e.g., closed state).When the apparatus is in the storage orientation, the valve 20 may be inthe open state, and when the apparatus is in the operation orientation,the valve 20 may be in the closed state. A gravity sensing device suchas the check valve in FIG. 3B may be the most cost effective andefficient option as compared to other types of valves.

In the open state, as shown by FIG. 4A, the valve 20, as illustrated inmore detail in FIG. 4B, may connect the drain line 21 to the fuel supplyline 23. The illustrated valve uses gravity to move the check ball 121on a sealing surface or seat 124 from a position to stop flow in onedirection as in FIG. 3B, to a position, approximately 90 degrees fromthe stop flow direction, where gravity causes the check ball to moveinto a pocket or passage 123 outside of the main flow passage 126 toallow fluid to flow. A plug 125 has a semi-spherical surface to locatethe ball in the flow position. The plug 125 provides a method to formthe sealing seat 124 in the valve body 20.

Through the operation of the valve 20, fuel from the carburetor bowl 12is returned to the fuel supply line 23 through the valve 20. Some of thefuel from the carburetor bowl 12 may return to the fuel tank 27. Whenfuel is returned to the fuel supply line 23, in a subsequent operationof the engine 10 where the engine is oriented in the operating position,any potential stale fuel will be mixed with, or diluted by, fresh fuelin the fuel supply line 23. When fuel is returned to the fuel tank 27,in a subsequent storage orientation of the engine 10, any potentialstale fuel will be mixed with, or diluted by, fresh fuel in the fueltank 27. Therefore, through the operation of valve 20 connecting thedrain line 23 to the fuel supply line 23, fuel that would normally ortypically remain in the carburetor bowl 12 over time and risk becomingless volatile is now automatically drained. That is, the carburetor bowl12 is automatically drained and replenished to increase the volatilityof the fuel in the carburetor bowl 12.

FIGS. 5A and 5B illustrate an example carburetor. A fuel inlet nipple410 provides fuel to carburetor bowl. A needle 411 has a tapereddiameter to meter the amount of fuel released into the air passage.FIGS. 5A and 5B include a location of the fuel inlet valve that will notallow fuel to fully drain from bowl in the tipped up state. FIG. 5B alsoillustrates the main air flow through the carburetor that passes througha venturi passage 421 having a smaller cross sectional area that reducesthe air pressure in the flow to draw fuel into the main chamber formixture with the air flow.

FIG. 6 illustrates a cross section of the carburetor including thelocation of the fuel inlet needle when tilted. Fuel in the carburetorbowl cannot drain via the inlet needle. Some fuel will drain out thebowl vent 510 passage and spill outside the engine. FIG. 6 illustrates across section that shows the fuel inlet valve in a position where fuelwill not fully drain from the bowl of the carburetor.

FIG. 7 illustrates a cross section of the carburetor including the fuelinlet needle located at low point when engine is tilted to allow fuel todrain back to the fuel tank. Bowl vent 521 located to prevent fuel fromdraining uncontrolled from the bowl.

FIG. 6 illustrates an example carburetor with the float is hingedperpendicular to the tilted angle so that movement is minimally affectedby gravity to move it to a position to open the fuel inlet needle 411.FIG. 7 illustrates the carburetor in which the float hinge orientationpromotes the movement of the float due to the carburetor tilt angle. Arotated float mechanism with the fuel inlet valve configured to allowall of the fuel to drain from the bowl when tilted. FIG. 6 illustratesthe carburetor in a normal or operation orientation with the axis of thenipple 413 in the horizontal plane (e.g., perpendicular to gravity) orwithin a predetermined angle to the horizontal plane. FIG. 7 illustratesthe carburetor in a titled orientation with the axis of the nipple 413in the vertical plane (e.g., parallel to gravity) or with apredetermined angle to the vertical plane or greater than apredetermined angle from the horizontal place.

In FIGS. 6 and 7, the fuel inlet needle 411 is reoriented from a typicalcarburetor to a position where when the carburetor is tilted, the inletneedle is at the lowest point of the fuel reservoir. This allows all ofthe fuel to drain back to the fuel tank through drain line 413. In thenormal inlet needle location, an amount of fuel can be trapped. Thistrapped fuel would eventually create gummy deposits as it evaporates.

When the carburetor is rotated from the normal rotation in FIG. 6 to thetilted orientation in FIG. 7, the fuel tank 412 rotated relative to thecarburetor. The fuel tank 412 is supported by a pivot 414, which mayinclude a rotatable connection with the carburetor housing.

The fuel tank 412 rotates according to the center of buoyancy of thefuel tank. The center of buoyancy is analogous to the center of mass ofa volume, e.g., the center of buoyancy of a sphere is the center of thesphere. A rigid link attached to the sphere and secure the other end ofthe link to the edge of a vessel of fluid with a hinge, the sphere wouldrotate about the hinge relative to the fluid level. If the sphere isfully submerged, the sphere would be directly above the hinge. In theembodiments of FIGS. 6 and 7, the float unseats the fuel inlet needlewhen the carburetor is tilted by two factors. One factor is offsettingthe center of buoyancy to begin the rotation of the float away from theinlet needle closed position when the carburetor bowl is full. The otherfactor is the effect of gravity to keep the float rotated to the inletneedle open position when the fuel is drained past the point where thefloat will float.

FIGS. 8A and 8B illustrate bowl vent locations in the carburetor. FIG.8A includes a cross section showing location of the fuel inlet needle531 when tilted. Fuel in bowl cannot drain via the inlet needle. Somefuel will drain out the bowl vent 521 and spill outside the engine.

FIG. 8B the fuel inlet needle located at low point when engine is tiltedto allow fuel to drain back to the fuel tank. Bowl vent located abovethe fuel level when the carburetor is tilted to prevent fuel fromdraining uncontrolled from the bowl.

Another technique for removing fuel from a carburetor bowl includes areciprocating pump (e.g., mechanically actuated diaphragm pump),actuated by a recoil starting device, for flushing or draining thecarburetor bowl. Other examples may include a piston pump, peristalticpump that is actuated by the recoil starter, a rotating element pumpwhich may be a gear, gerotor, or vane type, or a reciprocating pumppowered by an electric starter. FIG. 9A illustrates a top view of anengine 310 including a recoil pump 200, and FIG. 9B illustrates athree-dimensional view of the engine 310 including the recoil pump 200.

In one alternative (not illustrated) to the recoil pump 200 and recoilstarting device, or actuation powered by the recoil starting device, apump may be powered by an electric starter to provide the drainingfunction for the carburetor bowl. When the electric starter isenergized, the pumping function begins. When the engine starts, and thestarter returns to a de-energized state, the pumping function ceases.The action of a starter pinion gear, extending from its rest positionmay drive a reciprocating type pump for draining the carburetor bowl.

FIG. 10 illustrates a blower housing mounted fuel recirculation systemincluding a recoil pump 200 or a recoil starter mounted pump 200. FIGS.11A and 11B illustrate three-dimensional views of the blower housingmounted to a similar fuel recirculation system.

The recoil pump 200 may be used in combination with the valve 20 or asan alternative to the valve 20. The recoil pump 200 may pump fuel fromthe carburetor bowl 12 through a drain line 221 to the recoil pump 200and through a return line 224 from the recoil pump 200 to the fuel tank,which is illustrated behind fuel cap connection opening 226. The recoilpump 200 may be actuated by the starter recoil pulley 213. The starterrecoil pulley 213 may include one or more protrusions 211 that come incontact with the recoil pump 200. The protrusions 211 may be lobes orcams. The protrusions 211 may take various other shapes. Two protrusionsare illustrated in FIG. 10, and a system with five protrusions areillustrated in FIGS. 11A and 11B. Any number of protrusions may be used.

As described above, the fuel in the carburetor bowl 12, provided from afuel line 223 from the fuel tank, may become stale over time. When theengine 10 is subsequently started, by pulling the starter handle 277(starter rope not shown), the starter recoil pulley 213 rotates and oneor more of the protrusions 211 are brought into contact and out ofcontact with the recoil pump 200. The actuation of the recoil pump 200pulls the stale fuel from the carburetor bowl 12 through the drain line221. Fresh fuel flows through the fuel line from the fuel tank into thecarburetor bowl to provide a better starting air fuel mixture to theengine.

FIG. 12A illustrates fully discharged position of the recoil pump 200.FIG. 12B illustrates end of suction stroke position of the recoil pump200.

The recoil pump 200 may include a cam follower arm 101, a hard pointassembly 105, a diaphragm 107, a conical spring 109 in a pump chamber111, a check valve 113, an outlet pipe 115 to the fuel tank or a fuelsupply line, and an inlet pipe 117 (not shown in FIGS. 12A and 12B) fromthe carburetor bowl. In one example, an intermediate cantilevered leveris between the cam follower arm 101 and the hard point assembly 105.Additional, different, or fewer components may be included.

The cam follower arm 101 may be in contact with one or more protrusions311 on the starter recoil 313. As the starter recoil 313 rotates, aprotrusion 311 is brought in contact with the cam follower arm 101,under a displacement force illustrated by arrow A1, which presses thecam follower arm 101 from a deactivated state (e.g., suction phase)illustrated by FIG. 12B to the activated state (e.g., discharge phase)illustrated by FIG. 12A.

When depressed, the cam follower arm 101 applies a level forceillustrated by arrow A2 either to intermediate cantilevered lever whenincluded, or directly to the hard point assembly 105 when theintermediate cantilevered lever is not included. The intermediatecantilevered lever, when included, provides stabilization to theassembly.

The hard point assembly 105 receives the force from the cam follower arm101 or from the intermediate cantilevered lever. The hard point assembly105 is connected to the diaphragm 107 and the conical spring 109. Thehard point assembly 105 spreads the force from the cam follower arm tothe diaphragm 107 across the pump chamber 111 to spread the force ofevenly to depress the diaphragm 107 and the conical spring 109.

The conical spring 109 is adjacent to the check valve 113. The conicalspring 109 compresses to reduce the size of the pump chamber 111 toforce fuel through the check valve 113 through the outlet pipe 115 anddecompresses or expands to increase the size of the pump chamber 111 todraw fuel from the inlet pipe 117. The fuel in the pump chamber 111 mayenter the recoil pump 200 through an outer diameter compartment beforeflowing into the pump chamber 111. The conical spring 109 transitionsfrom decompressed to compressed each time the cam follower arm 101 isoperated by the protrusion 311.

The conical spring 109 may return to the decompressed state throughenergy stored in the conical spring 109 and apply a spring force asillustrated by arrow A3 to the cam follower arm 101. The cam follow arm101 provides a lever force illustrated by arrow A4 to push the camfollower arm 101 against the protrusions 311 on the starter recoil 313.

The check valve 113 may include a duckbill valve having a center sectionshaped like a hull or a duck bill. Under pressure, the check valve 113opens to allow flow of fuel through the check valve 113. The check valve113 may be replaced by two ball and spring check valves, reed valves orother check valve devices.

The cam follower arm 101, which may be referred to as a rocker arm,provides leverage between the force received the protrusion 311 and theforce applied to the conical spring 109. In other words, an applieddistance by the protrusion 311, which may be the height of theprotrusion 311, is less than a compression distance applied to theconical spring 109. The cam follower arm 101 may operate as a lever thattranslates a first distance of the protrusion 311 to a second distanceof the conical spring 109, with the first distance being smaller thanthe second distance. The cam follower arm 101 provides more stroke tothe pump with less of a lift from the recoil. In one example, theprotrusion 311 as a depth of 1-3 millimeters and the distance that theconical spring 109 is depressed is 5-10 millimeters.

The protrusions 211 come into contact with the recoil pump 200 at thecam follower arm 101 in FIGS. 12A and 12B and, alternatively, at roller213 shown in FIG. 10. The roller 213 and the cam surface of the camfollower arm 101 are interchangeable. The cam surface of the followerarm 101 may be referred to as a sliding piston. In some examples, thecam surface may be preferable to reduce the number of moving parts ofthe system. In some examples, the roller 213 may be preferable becausethe sliding piston creates friction and generates wear. In somescenarios, the force from the pump lever from the cam follower arm 101may be greater than the spring return force in the recoil, which hampersor prevents the recoil from winding after a pull. The roller 213 mayreduce this friction to allow the recoil to operate properly. In someexamples, the roller 213 may be added to the cam follower arm 101. Inthis way, if the roller 213 becomes damaged and is removed or otherwisefalls off, the cam surface of the cam follower arm 101 remains. Therecoil starter is configured to simultaneously start the engine andactuate the pump. The term simultaneously may mean within apredetermined amount of time (e.g., 1-5 seconds) or as part of the sameaction (e.g., pulling the starter).

FIGS. 13A and 13B further illustrate the operation of the recoil pump.As shown by arrow A5, fuel under pressure flows through the duck bill.As shown by arrow A6, fuel is pushed out of the pump chamber through theoutlet pipe 115. As the conical spring returns to the decompressedstate, fuel is drawn into the inlet pipe 117, as shown by arrow A7, andinto the pump chamber, as shown by arrow A8.

FIG. 13C illustrates an exploded view of a recoil pump 200. The recoilpump 200 may include a follower arm 141, a diaphragm 107, a pull rod214, a conical spring 109, and a support bracket 215. A pump chamber isformed between the valve assembly 210 and the diaphragm 107. The valveassembly 210 may include different types of valves, and the illustratedexample includes plug balls 208 and check balls 209 for an outlet pipe117 to the fuel tank or a fuel supply line and an inlet pipe 115. Theplug balls 208 and check balls 209 may be formed from metal or steel.Other types of check valves or reed valves with a flap of material(e.g., rubber or Mylar). Additional, different, or fewer components maybe included. FIG. 13D illustrates a top view of the recoil pump of FIG.13C and the blower housing.

In the examples of FIGS. 13A and 13B, the cam follower arm 101 isactuated and to force fuel out of the chamber 111, and the energy storedin the spring 109 draws fuel into the chamber 111. In some examples,depending on the speed of the recoil and the number of protrusions, thisarrangement may move too quickly to give time for the fuel to be drawninto and/or forced out of the chamber 111.

As an alternative, the example of FIGS. 13C and 13D the follower arm 141is actuated by the movement of the roller 213 along the protrusions todraw fuel into the chamber 111, and the energy stored in the spring 109forces the fuel out of the chamber 111. That is, the spring 109 isconnected to the diaphragm 107 and biased to push the diaphragm 107 intothe chamber 111, which pushes the fuel out of the chamber 111. The pullrod 214 is also connected to the diaphragm 107 on one end and to thefollower arm 141 on the other end. As the follower arm 141 moves inresponse to the roller 212 rolling over the convex portion of theprotrusion, the pull rod 214 pulls the diaphragm 107 to pull fuel intothe chamber 111. As the roller 212 moves to a concave portion of theprotrusion, the pull rod 214 no longer pulls the diaphragm 107, whichallows the force stored in the spring 107 to push the diaphragm 107 intothe chamber 111, which pushes the fuel out of the chamber 111.

In this example, even if the roller 212, follower arm 141, and pull rod214 oscillate quickly, the process is not disrupted. The diaphragm 107applies a small force in a direction away from the recoil pump 200. Ifthe chamber 111 is empty, the diaphragm 107 and pull rod 214 holds thefollower arm 141 such that the arm 141 does not contact the protrusions211. Accordingly, as fuel flows out of the chamber 11, the roller 212does not contact the cam until a specific volume of fuel has flowed outof the chamber 111. When the roller 212 is out of contact with theprotrusions 211, no force or torque is applied to the recoil. Thus, theroller 212, the follower arm 141, and the pull rod 214 are in a neutralor floating state.

FIGS. 14A and 14B illustrate the fuel recirculation system including thepump 200 mounted with the fuel tank on an engine.

FIGS. 15A and 15B illustrate another embodiment of fuel recirculationsystem. In this embodiment, the recoil pump 200 is mounted directly onthe fuel tank 240. FIGS. 16A and 16B illustrate a fuel tank mounted pumpfor the embodiment of FIGS. 15A and 15B.

FIGS. 17A and 17B illustrate detailed views for the fuel tank mountedpump 300. One advantage of the fuel tank mounted pump is the pump outlethose is no longer necessary. The discharge port opens directly into thefuel tank.

The fuel tank mounted pump includes a conical spring 109, a diaphragm107, a lever 251, a cam follower 250, an outlet 253 for the check valve,and an inlet 255 for the check valve. The cam follower 250 receives aforce in a first direction from the cam lobes of the recoil started. Theforce in the first direction is translated to a second direction throughlever 251. The second force is applied to the piston of the pump, whichdepressed the conical spring 109 and the diaphragm 107, which changesthe size of the pump cavity to push fuel out through the outlet 253 anddraw new fuel through the inlet 255 into the check valve.

FIG. 18 illustrates an example flowchart for operation of an orientationcontrolled carburetor drain. Additional, different, or fewer acts may beincluded.

At act S101, a first fuel path is provided to a carburetor in a firstorientation of an engine. The first orientation of the engine may be theoperating orientation of the engine. For example, when the engine isincluded on a wheeled device, the operating orientation is theorientation in which all or a majority of the wheels are resting on theground or in a plane substantially perpendicular to the direction ofgravity.

At act S103, the engine including the carburetor is transitioned ormoved from the first orientation to a second orientation. In oneexample, the engine may be mounted on a wheeled machine that is placedin a storing position. For example, the wheeled machine may be tipped upfor storing in an orientation perpendicular to an operating orientationor hanging on a wall or mount in the orientation perpendicular to theoperating position.

At act S103, a drain path from the carburetor in the second orientationof the engine. The drain path may be opened through a check valve. Thedrain path may allow fuel to flow through the drain path from thecarburetor to return to the fuel tank of the engine. The drain path maybe referred to as a return path.

FIG. 19 illustrates an example flowchart for a recoil actuatedcarburetor drain pump. Additional, different, or fewer acts may beincluded.

At act S201, receive a force at the recoil actuated carburetor drainpump from a protrusion on a recoil starter. The recoil starter mayinclude protrusions or lobes that are spaced apart. As the recoilstarted rotates, the protrusions come in and out of contact with therecoil actuated carburetor drain pump.

At act S203, the recoil actuated carburetor drain pump translates theforce from a first distance based on a dimension of the protrusion to asecond distance. For example, the recoil actuated carburetor drain pumpmay include a lever in which the ratio of the lever arms is proportionalto the first distance and the second distance.

At act S205, the recoil actuated carburetor drain pump provides a forcefor the second distance to compress a pump spring. As a result ofcompressing the pump spring, the recoil actuated carburetor drain pumpis activated to drain fuel from a carburetor, as shown by act S207.

The small internal combustion engine may be applicable to chainsaws,lawn mowers, wood chippers, stump grinders, concrete trowels, miniexcavators, concrete saws, portable saw mills, weed trimmers,all-terrain vehicles, wood splitters, pressure washers, garden tillers,tractors, plows, snow blowers, welding equipment, generators, and otherdevices.

The engine 10 may include one cylinder, two cylinders or another numberof cylinders. The one or more cylinders may generate noise or soundwaves as a result of the oscillations of one or more pistons through theone or more cylinders, which are shaped to receive the one or morepistons. The one or more pistons may be guided through the one or morecylinders by a connecting rod that is connected to a crankshaft by acrankpin. A combustion chamber includes a combustion chamber adjacent toa head of the piston. The combustion chamber is formed in a cylinderhead. In one phase of a combustion cycle for the piston, the exhaustport is blocked from the combustion chamber by the piston, and in asubsequent phase, the exhaust port is in gaseous connection with thecombustion chamber to release exhaust gas through the exhaust port to amuffler.

The phrases “coupled with” or “coupled to” include directly connected toor indirectly connected through one or more intermediate components.Additional, different, or fewer components may be provided. Additional,different, or fewer components may be included.

The acts of FIG. 18 may be initiated by one or more controllersincluding a specialized processor, one or more memories and acommunication interface. The one or more controllers may operate thecheck valve by generating open and close commands for the check valve.The open and close commands may be generated in response to data from asensor (e.g., magnetic sensor or gravity sensor) that describes theorientation of the engine. Instructions for the one or more controllersmay be embodied on a non-transitory computer readable medium.

The recoil actuated carburetor drain pump may be controlled according toone or more controllers including a specialized processor, one or morememories and a communication interface. The one or more controllers mayenable or disable the recoil actuated carburetor drain pump. The one ormore controllers may generate an enable command when the carburetorshould be drained. For example, the controller may determine when apredetermined time (e.g., one week or one month) has elapsed. Thepredetermined time may be selected so that the drain pump is actuatedafter the engine is stored. Instructions for the one or more controllersmay be embodied on a non-transitory computer readable medium.

FIGS. 20A and 20B illustrate an engine 601 including a recirculationsystem 600 using an enclosed fluid. FIG. 21 illustrates an examplerecirculation system 600 using an enclosed fluid in a first state. FIG.22 illustrates an example recirculation system 600 using an enclosedfluid in a second state. The recirculation system 600 may pump fuel fromthe carburetor bowl 612 through a drain line 621 to the recirculationsystem 600 and through a return line 624 from the recirculation system200 to the fuel tank 630. The recirculation system 600 may include nomechanical parts to drive the pump. Instead, the diaphragm 607 pumpsfuel through the action of gas expansion. Additional, different, orfewer components may be included.

The recirculation system 600 may include two or more chambers such as afuel chamber 611 and a fluid chamber 610 integrated into a single deviceand separated by a diaphragm 607. The diaphragm 607 may be formed ofrubber, plastic, or another durable but flexible material. The fluidchamber 610 includes a fluid that expands and contracts in response tothe ambient environment. For example, the fluid may expand or contractin response to temperature changes. The recirculation system 600 may beplaced near (e.g., within a predetermined distance of) a heat sourcesuch as muffler 640. In some examples, the fuel chamber 611 and fluidchamber 610 are separated. The fluid chamber 610 may be spaced apartfrom the recirculation system 600 and provide fluid to a third chamberin communication with the fuel chamber 611.

The fuel chamber 611 includes a drain line 621 to the carburetor bowland the return line 624 to fuel tank. A check valve 620 may include aplug 608 and a check ball 609. The check valve 620 directs the flow offuel from the carburetor bowl and to the fuel tank 630. The plug 608 mayprovide a clearance hole for the check ball 609. The plug 608 limits howfar the check ball 609 can travel in the cavity. In FIG. 21, the checkball 609 is in seated position in which fuel is pushed out of the fuelchamber 611. In FIG. 22, the check ball 609 is in an inlet flowposition. The check ball 609 may be a drain return portion of the checkvalve 620 regulates the flow of fuel from the carburetor and preventsthe flow of fuel back to the carburetor bowl from the recirculationsystem 600. The check ball 609 may be a fuel shutoff valve portion ofthe check valve 620 that regulates the flow of fuel to fuel tank 630 andprevents the flow of fuel from the fuel tank to the recirculation system600. Alternatively, a reed valve or another type of valve may be usedfor either or both of the drain return portion or the fuel shutoff valveportion.

The fluid may be any gas or liquid. The fluid may be dry air. Otherexample fluids may include air, helium, oil, or water. The fluid chamber610 is sealed from the ambient environment and the fuel chamber 611. Theair chamber 610 may be connected to no tubes and be sealed from allother components. The recirculation system 600 operates on the principalof thermal expansion of as gas. Thus, the fluid in the fluid chamber 610has a first volume and a first temperature and a second volume at asecond temperature, with the first volume being greater than the secondvolume and the first temperature being greater than the secondtemperature.

For example, FIG. 21 illustrates a state of the recirculation system 600in which the fluid in the fluid chamber 610 has expanded, for example,due to heat causes by running the engine 600. The spring 609 has storedenergy that places a force on the diaphragm 607 in a direction thaturges the diaphragm 607 to make the fluid chamber 610 smaller (e.g., tothe left in FIG. 21). However, because the fluid is expanded, the fluidprevents the diaphragm 607 from compressing the fluid. In this way, whenthe engine 600 is running, the fluid in the fluid chamber 610 expandsand pushes the diaphragm 607 and spring 609 toward the check valve 620,causing the check valve 620 to open a path from the fuel chamber 611 tothe fuel tank and pushing the fuel in the fuel chamber 611 into the fueltank 630.

However, as the fluid cools, the fluid takes less space, which allowsthe spring 608 to press the diaphragm 607 into the space previouslyoccupied by the fluid. FIG. 22 illustrates a state of the recirculationsystem 600 in which the fluid in the fluid chamber 610 has compressed,for example, due to the engine 600 being cooled (i.e., not operated forsome time). The diaphragm 607 and spring 609 create a vacuum to drawfuel out of the carburetor bowl for storage. The compression of thefluid chamber 610 allows for expansion of the fuel chamber 611 andcauses the check valve 620 to open a path from the carburetor bowl tothe fuel chamber 611. The fuel shutoff valve portion of the check valve620 also prevents fuel from the fuel tank 630 from being drawn into thefuel chamber 611.

The next time that the engine 600 is started and heats up, the fluid inthe fluid chamber 610 again heats up, pushes the diaphragm 607 to theright, the fuel shutoff valve portion of the check valve 620 is opened,and the stored fuel (originally from the carburetor bowl) is pushed intothe fuel tank 630.

The fluid chamber 610 may include spacer 650 as a diaphragm travellimiting device to maintain a minimum fluid volume in the chamber 610.The spacer 650 provides an accurate volume of fluid during assembly ofthe pump or recirculation system 600 and also prevents the diaphragm 607from adhering to the inner chamber wall during prolonged periods ofengine storage. The spacer 650 may be formed of metal, plastic oranother material safe for extended exposure to the fuel. The dimensionsof the spacer 650 may be selected as a proportion or predeterminedfraction of the fluid chamber 610 or of the carburetor bowl.

In addition to within a predetermined distance to the muffler 640 asshown in FIGS. 20A and 20B, the recirculation system 600 may be securedto the engine 601 in a variety of locations. The recirculation system600 may be formed integrally with a heat shield 641 for muffler 640. Therecirculation system 600 may be installed near the muffler 640 oranother heat producing component using a bracket. The size (e.g.,thickness) of the bracket and/or the number of holes in the bracket maybe adjusted to modify the heat flow from the head producing componentsto the recirculation system 600. The recirculation system 600 may bemounted near the outlet side of coolant system where hot air passes fromthe engine. The recirculation system 600 may be mounted near the crankcase, which also heats up during operation of the engine. Otherlocations for the recirculation system 600 are possible.

In another example, the recirculation system 600 may be mounted near aheat pipe. The heat pipe allows heat to travel from the heat producingelement to the reticulation system 600. The heat pipe has a high thermalconductivity.

In another example, exhaust may be routed from the muffler 640 to therecirculation system 600 using a tube. The exhaust retains heat to causethe expansion of the fluid in the recirculation system 600.

In another example, the recirculation system 600 includes an auxiliaryheat source (e.g., a battery powered heating element) that heats up inresponse to the engine running. The auxiliary heat source may beconnected to the battery of the engine. The auxiliary heat source heatsthe fluid in the fluid chamber 610.

The illustrations of the embodiments described herein are intended toprovide a general understanding of the structure of the variousembodiments. The illustrations are not intended to serve as a completedescription of all of the elements and features of apparatus and systemsthat utilize the structures or methods described herein. Many otherembodiments may be apparent to those skilled in the art upon reviewingthe disclosure. Other embodiments may be utilized and derived from thedisclosure, such that structural and logical substitutions and changesmay be made without departing from the scope of the disclosure.Additionally, the illustrations are merely representational and may notbe drawn to scale. Certain proportions within the illustrations may beexaggerated, while other proportions may be minimized. Accordingly, thedisclosure and the figures are to be regarded as illustrative ratherthan restrictive.

While this specification contains many specifics, these should not beconstrued as limitations on the scope of the invention or of what may beclaimed, but rather as descriptions of features specific to particularembodiments of the invention. Certain features that are described inthis specification in the context of separate embodiments can also beimplemented in combination in a single embodiment. Conversely, variousfeatures that are described in the context of a single embodiment canalso be implemented in multiple embodiments separately or in anysuitable sub-combination. Moreover, although features may be describedabove as acting in certain combinations and even initially claimed assuch, one or more features from a claimed combination can in some casesbe excised from the combination, and the claimed combination may bedirected to a sub-combination or variation of a sub-combination.

Similarly, while operations are depicted in the drawings and describedherein in a particular order, this should not be understood as requiringthat such operations be performed in the particular order shown or insequential order, or that all illustrated operations be performed, toachieve desirable results. In certain circumstances, multitasking andparallel processing may be advantageous. Moreover, the separation ofvarious system components in the embodiments described above should notbe understood as requiring such separation in all embodiments, and itshould be understood that the described program components and systemscan generally be integrated together in a single software product orpackaged into multiple software products.

One or more embodiments of the disclosure may be referred to herein,individually and/or collectively, by the term “invention” merely forconvenience and without intending to voluntarily limit the scope of thisapplication to any particular invention or inventive concept. Moreover,although specific embodiments have been illustrated and describedherein, it should be appreciated that any subsequent arrangementdesigned to achieve the same or similar purpose may be substituted forthe specific embodiments shown. This disclosure is intended to cover anyand all subsequent adaptations or variations of various embodiments.Combinations of the above embodiments, and other embodiments notspecifically described herein, will be apparent to those of skill in theart upon reviewing the description.

It is intended that the foregoing detailed description be regarded asillustrative rather than limiting and that it is understood that thefollowing claims including all equivalents are intended to define thescope of the invention. The claims should not be read as limited to thedescribed order or elements unless stated to that effect. Therefore, allembodiments that come within the scope and spirit of the followingclaims and equivalents thereto are claimed as the invention.

We claim:
 1. A method comprising: receiving, at a rod, a force from arecoil starter; providing, from the rod, a first force for a pumpincluding a diaphragm in contact with the rod; providing, from a spring,a second force for the pump; and draining fuel from a carburetor via thepump.
 2. The method of claim 1, wherein draining fuel from thecarburetor via the pump further comprises: pumping fuel to a fuel tank.3. The method of claim 1, further comprising: opening a valve inresponse to operation of the pump.
 4. A fuel recirculation system for anengine, the fuel recirculation system comprising: a chamber configuredto store fuel; a diaphragm configured to push at least a portion of thefuel out of the chamber; a rod driven by a recoil and configured toapply a first force to the diaphragm; and a spring configured to apply asecond force to the diaphragm.
 5. The fuel recirculation system of claim4, wherein the spring is a conical spring.
 6. The fuel recirculationsystem of claim 5, wherein the rod is movable by a recoil starter. 7.The fuel recirculation system of claim 4, further comprising: acarburetor drain line in communication with the chamber.
 8. The fuelrecirculation system of claim 7, further comprising: a valve on thecarburetor drain line.
 9. The fuel recirculation system of claim 8,wherein the valve is configured to drain the chamber in a predeterminedorientation.
 10. The fuel recirculation system of claim 9, wherein thepredetermined orientation is a storage orientation.
 11. A carburetorcomprising: a carburetor bowl configured to store fuel and provide thefuel to an air passage; a fuel supply pipe connected a fuel tank and thecarburetor bowl; a fuel drain pipe connected to the carburetor bowl; achamber configured to store fuel; a diaphragm configured to push atleast a portion of the fuel out of the chamber to the fuel drain pipe; arod driven by a recoil and configured to apply a first force to thediaphragm; and a spring configured to apply a second force to thediaphragm.
 12. The carburetor of claim 11, further comprising: a valveon the fuel drain line.
 13. The carburetor of claim 12, wherein thevalve is configured to drain the chamber in a predetermined orientation.14. The carburetor of claim 13, wherein the predetermined orientation isa storage orientation.
 15. The carburetor of claim 11, wherein the rodis movable by a recoil starter.
 16. The carburetor of claim 11, whereinthe fuel drain pipe returns fuel to a fuel tank.
 17. The carburetor ofclaim 11, wherein the fuel drain pipe returns fuel to the fuel supplyline.
 18. The carburetor of claim 11, wherein the spring is a conicalspring.